This invention relates to a method for adapting a relational database management system (DBMS) in a digital computer so that the system will have the ability to utilize foreign information. More particularly, this invention relates to a method for adapting a DBMS so that it can utilize data which is foreign in its location, foreign in its file format, or foreign in its order. These forms of foreign data may, by way of example, include real time data, such as data concerning a process that is being monitored in real time; distributed data, such as data that is stored at different physical locations in a large industrial plant; distributed real time data, which presents both the problems of real time data as well as the problems of distributed data; data which is in a format which is foreign (different from) the format which is required for the operation of the DBMS; data which is in a format which is compatible but which is so ordered that it is not useful to the DBMS; and computed data, data which is not stored as files but is computed at the time it is needed to fulfill a query of a client, a user of the system.
For the purposes of this description a relational database management system (DBMS) is defined as a system for managing data in which data is organized in one or more rectangular tables of rows and columns, and wherein the contents of each column is data of the same type throughout all of the rows of the column. Thus, in a relational database the data organization fits set theory, and the records in different files can be linked (cross-referenced) by the content of columns that are common in the different files.
While there are many relational database management systems available, none of these systems is able to use foreign data without a conversion of the data into an appropriate format by entry of the data into a standard file of the database prior to the need to query the data. This placing of the data in the proper format becomes particularly difficult when it is necessary to utilize data which is being obtained in real time and which must be queried in real time. In such cases, it is important to have the ability to query such data without taking the time to first incorporate it into the database in the desired format. It is therefore an object of this invention to provide a method for adapting or constructing a relational DBMS to make it capable of incorporating foreign data so that the normal DBMS functions, such as reading and writing that data, may be accomplished.
More particularly, it is an object of this invention to provide a method for adapting or constructing a relational DBMS for incorporating real time data for use by the DBMS.
Since there are many good commercially available DBMSes, it is particularly useful to adapt an existing one for the incorporation of foreign data, in some circumstances one might incorporate the present invention in the construction of a relational DBMS from scratch. Therefore, since the same steps are required in either case, the words "adapting" and "constructing" are used interchangeably in this description, as they are applied to the invention.